Polyols are valuable materials that find use in the manufacture of cold weather fluids, cosmetics, polyesters and many other synthetic products. Generating polyols from saccharides instead of fossil fuel-derived olefins can be a more environmentally friendly and a more economically attractive process. Previously, polyols have been generated from polyhydroxy compounds, see WO 2006/092085 and U.S. 2004/0175806. Recently, catalytic conversion of saccharide into ethylene glycol over supported carbide catalysts was disclosed in Catalysis Today, 147, (2009) 77-85. U.S. 2010/0256424, U.S. 2010/0255983, and WO 2010/060345 teach a method of preparing ethylene glycol from saccharide and a tungsten carbide catalyst to catalyze the reaction. Tungsten carbide catalysts have also been published as successful for batch-mode direct catalytic conversion of saccharide to ethylene glycol in Angew. Chem. Int. Ed 2008, 47, 8510-8513 and supporting information. A small amount of nickel was added to a tungsten carbide catalyst in Chem. Comm. 2010, 46, 862-864. Bimetallic catalysts have been disclosed in ChemSusChem, 2010, 3, 63-66. Additional references disclosing catalysts known in the art for the direct conversion of cellulose to ethylene glycol or propylene glycol include WO2010/060345; U.S. Pat. No. 7,767,867; Chem. Commun., 2010, 46, 6935-6937; Chin. J. Catal., 2006, 27(10): 899-903; and Apcseet UPC 2009 7th Asia Pacific Congress on Sustainable Energy and Environmental Technologies, “One-pot Conversion of Jerusalem Artichoke Tubers into Polyols.
However, there remains a need for new catalyst systems effective for direct conversion of saccharide to polyol, and especially for catalyst systems that may be better suited for larger scale production or ongoing production. The catalyst system comprising at least one unsupported component and at least one supported component for generating at least one polyol from a saccharide containing feedstock described herein addresses this need.